Pearl in the Mist book cover.

Even after a year as a Dumas, Ruby still wonders at the splendor of the family's New Orleans mansion, and rejoices in the love of the father she had never known. But true happiness in her new home is as elusive as a swamp mist. Ruby must carefully avoid a venomous enemy: her stepmother, who cringes and sneers at her backwater upbringing. And Ruby's every effort to befriend her twin sister,Gisselle -- especially since Gisselle's crippling accident -- is answered with bitterness and vicious backstabbing.

So idyllic Greenwood -- the exclusive girls' boarding school that her father has chosen for his daughters' senior year -- seems to promise some peace from the conniving Daphne, and maybe even a fresh start with Gisselle. But Ruby's kind isn't welcome at Greenwood, and the legendarily strict headmistress, Mrs. Ironwood, plots with her stepmother to make her life miserable. Meanwhile, Gisselle is on a mission to break every school rule, leaving Ruby to suffer the humiliating punishments. But Ruby doesn't lose hope -- until a terrible tragedy leaves her alone in a world that never really wanted her. Ruby will have to summon every last ounce of her Cajun strength to reclaim her home, her future, and the happiness she once knew....

Ruby Landry's school life immediately gets off to a bad start when the school's headmistress, Mrs. Ironwood, informs her that Daphne has made her aware of her Cajun background (implying that she is badly brought up and a troublemaker) and that she will be keeping an eye on her. Giselle quickly ingratiates herself to the small clique of girls she and Ruby first meet when arriving at Greenwood, using them to amuse herself. Despite her problems with her sister, Ruby manages to make friends with the blind piano player Louis Turnbull, who is the school founder's only grandson; the art teacher, Miss Stevens; and a fellow student, Abby, who shares Ruby's intellectual ambitions. She even rekindles her relationship with Beau Andreas. As time goes on however, Giselle becomes jealous of Ruby's friendship with Abby. She exposes Abby as a quadroon at the school's Halloween dance, a secret Abby had been keeping in order to study at Greenwood. Abby leaves the dance in the middle of a violent storm, but returns the next morning to formally withdraw, as Mrs Ironwood will not permit her to stay with her ethnic background. Disgusted by Giselle's behavior, Ruby is poised to leave as well, but Abby urges her to stay and continue in her artistic endeavors. Miss Stevens comforts Ruby later, telling her that she will always have her help and guidance if she needs it. Days later, Ruby discovers to her horror that Pierre has died of a heart attack. After the funeral, Mrs Ironwood threatens to expel Ruby, saying she has eyewitness accounts of her having sexual liaisons with the school caretaker. Fortunately, Louis and Miss Stevens come to her aid, testifying that Ruby could not have been in those places at that time, as she was with Louis. Miss Stevens vouches for Ruby's character and Ruby is exonerated, though the mystery remains.

During the Christmas vacation, Ruby walks in on Giselle standing up without the aid of a stick. She forces her sister to confess that she was the one who met the school caretaker, but Giselle dismisses what happened, since Ruby was not expelled. Although walking is still difficult, she says her legs are getting stronger. Ruby threatens to tell Daphne that Giselle is using her paralysis to make people run and fetch for her, but Giselle merely retorts that she will tell Daphne about Ruby resuming her relationship with Beau. After this less than merry Christmas, Ruby and Giselle return to Greenwood, where Ruby discovers that Miss Stevens has resigned over a scandal where she was accused of seducing a female student. Ruby knows this to be a lie, but is powerless to do anything to help Miss Stevens. Her troubles are further compounded when she learns that she has become pregnant with Beau's child after they had unprotected sex during a visit to the campus. Ruby leaves Greenwood and returns to New Orleans, where Daphne informs her that Beau's parents have sent him away to attend school in France after learning about the pregnancy. She then arranges for Ruby to have an illegal abortion. Ruby feels so depressed and alone that she does not object, but after seeing the dilapidated state of the clinic Daphne sends her to, she runs back to her home town of Houma. On her way there, she tries to get in touch with Beau, but discovers that he has already left for France. Despondent, Ruby contacts her half-brother, Paul Tate, instead. He is glad to hear from her, but warns her that Grandperè Jack is in a terrible state, having gone semi-mad after she left. They find him near the old shack she shared with Grandmere Catherine, but after a brief altercation with Paul, Jack runs off and drowns in the swamps. Later Paul offers her a home for her and her baby in a newly built mansion named Cypress Woods, but Ruby is very reluctant to accept the offer, as she knows people will assume that the child is Paul's if she accepts his help. She also suspects that he is still in love with her and does not want to encourage his feelings.

At the climax, Ruby gives birth to her daughter, Pearl, in a hurricane which blows away many (if not most) of the surrounding homes. This is later described as one of the worst storms in decades. At the end of the story, Ruby is uplifted by the birth of her baby and believes her future is bright and hopeful.